Ultrasound diagnostic device, ultrasound diagnostic method, and ultrasound diagnostic program

ABSTRACT

An ultrasound diagnostic device includes: a probe including plural elements that generate and transmit ultrasound waves and receive ultrasound waves reflected from an inspection target; a transmission unit that transmits ultrasound waves from the plural elements so as to transmit an ultrasound beam by forming a transmission focus in a first direction set in advance; and a second reception focusing unit that performs reception focusing for each reception signal received by each element of the probe according to reflection on a path in a second direction other than the first direction, among transmission wave paths of the ultrasound beam transmitted into the inspection target by the transmission unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication No. PCT/JP2014/061198, filed on Apr. 21, 2014, thedisclosure of which is incorporated herein by reference in its entirety.Further, this application claims priority from Japanese PatentApplication No. 2013-157656, filed on Jul. 30, 2013, the disclosure ofwhich is incorporated by reference herein in its entirety.

BACKGROUND

Technical Field

The present disclosure relates to an ultrasound diagnostic device, anultrasound diagnostic method, and a storage medium storing an ultrasounddiagnostic program.

Related Art

When visualizing a needle by the transmission and reception ofultrasound waves, if the angle of the needle becomes an acute angle, thereflection deviates from the reception opening, as shown in FIG. 18A. Inthis case, it is not possible to receive the reflected wave from theneedle. Therefore, as shown in FIG. 18B, a method of receiving thereflected wave from the needle by transmitting a transmission beamobliquely so that the transmission beam is perpendicular to the needleis known.

However, an image generated by tilting the transmission beam is notsuitable to see the tissue since the image quality is degraded due tothe influence of side lobes or the like.

Therefore, JP2012-213606A proposes that a first ultrasound image isgenerated by performing ultrasound transmission in a first direction, asecond ultrasound image group is generated by transmitting ultrasoundwaves in a plurality of directions for the purpose of needle imaging, aneedle image in which the needle is visualized is generated by analyzingthe first image and the second image group or the brightnessdistribution of the second image group, and the first image and theneedle image are combined.

As a method of visualizing the needle image, in addition to the methoddisclosed in JP2012-213606A, a technique disclosed in JP2010-51379A andthe like have also been proposed.

JP2010-51379A proposes that an ultrasound beam having an intensitydistribution around a first direction is transmitted from ultrasoundtransducers of a first group and an ultrasound image in a seconddirection different from the first direction is generated based onreception signals obtained by the reception of ultrasound echo signalsof ultrasound transducers of a second group.

In the technique disclosed in JP2012-213606A, however, one tissueimaging and multiple needle imagings are required. For this reason, theframe rate is reduced.

In addition, in the technique disclosed in JP2010-51379A, a plane wavefor which transmission focusing is not required is used. Accordingly,depending on the angle of the needle, reflected waves cannot be obtainedat all. As a result, the needle may not be able to be visualized.

The present disclosure has been made in view of the above situation, andprovides an ultrasound diagnostic device, an ultrasound diagnosticmethod, and a non-transitory storage medium storing an ultrasounddiagnostic program capable of visualizing a reflector, such as a needle,other than the tissue without lowering the frame rate.

SUMMARY

A first aspect of the present disclosure is an ultrasound diagnosticdevice including: a probe including plural elements that generate andtransmit ultrasound waves and receive ultrasound waves reflected from aninspection target; a transmission unit that transmits ultrasound wavesfrom the plurality of elements so as to transmit an ultrasound beam byforming a transmission focus in a predetermined first direction; and asecond reception focusing unit that performs reception focusing for eachreception signal received by each element of the probe according toreflection on a path in a second direction other than the firstdirection, among transmission wave paths of the ultrasound beamtransmitted into the inspection target by the transmission unit.

According to the ultrasound diagnostic device of the first aspect, theprobe includes plural elements that generate and transmit ultrasoundwaves and receive ultrasound waves reflected from the inspection target.

The transmission unit transmits ultrasound waves from the pluralelements so as to transmit an ultrasound beam by forming a transmissionfocus in the first direction set in advance.

The second reception focusing unit performs reception focusing for eachreception signal received by each element of the probe according to thereflection on the path in the second direction other than the firstdirection, among the transmission paths of the ultrasound beamtransmitted into the inspection target by the transmission unit.

Thus, since the transmission focusing is performed by the transmissionunit, ultrasound echoes generated by reflection from the reflectionpoints in directions other than the first direction are also received bythe plural elements. Therefore, it is possible to visualize a reflector,such as a needle, by performing reception focusing according to thereflection on the path in the second direction using the secondreception focusing unit. In addition, it is also possible to visualizethe tissue by performing the reception focusing in the first direction.Therefore, it is possible to visualize a reflector, such as a needle,without lowering the frame rate. That is, by further including a firstreception focusing unit that performs reception focusing according toreflection on a path in the first direction, it is possible to visualizethe tissue while visualizing a reflector, such as a needle, withoutlowering the frame rate. In this case, a combination unit that combinesresults of the reception focusing of the first and second receptionfocusing units may be further included.

In the first aspect, the transmission unit may transmit ultrasound wavesfrom the plural elements so as to transmit an ultrasound beam by forminga transmission focus in the first direction in each of two or moredifferent openings of the probe, and the second reception focusing unitmay perform reception focusing for the reception signal for each openingaccording to a common reflection point in the second direction.

The second reception focusing unit may perform reception focusing basedon a delay time set on the assumption that each transmission waveconverges and diverges in a shape of a spherical wave in a shallowerregion and a deeper region than the transmission focus. The secondreception focusing unit may assume specular reflection at each point inthe second direction, assume a sound source at a different point fromthe point, and perform reception focusing for each point in the seconddirection based on a delay time for the assumed sound source.

The first aspect may further include a determination unit thatdetermines a direction of a needle based on a result of the receptionfocusing of the second reception focusing unit.

In addition, a designation unit that designates the second direction maybe further included. In this case, the designation unit may designatethe second direction based on information related to a directionobtained from a fixing portion that fixes a needle. The second directionmay be designated based on a result of last reception focusing performedby the second reception focusing unit.

A second aspect of the present disclosure is an ultrasound diagnosticmethod including: transmitting an ultrasound beam by forming atransmission focus in a predetermined first direction from pluralelements of a probe, the prove including the plural elements thatgenerate and transmit ultrasound waves and receive ultrasound wavesreflected from an inspection target; and performing second receptionfocusing for each reception signal received by each element of the probeaccording to reflection on a path in a second direction other than thefirst direction, among transmission wave paths of the ultrasound beamtransmitted into the inspection target.

According to the ultrasound diagnostic method of the second aspect,ultrasound waves are transmitted from the plural elements of the probe,which includes the plural elements that generate and transmit ultrasoundwaves and receive ultrasound waves reflected from the inspection target,so as to transmit an ultrasound beam by forming a transmission focus ina first direction set in advance.

In addition, the second reception focusing is performed for eachreception signal received by each element of the probe according to thereflection on the path in the second direction other than the firstdirection, among the transmission wave paths of the ultrasound beamtransmitted into the inspection target.

Thus, by performing the transmission focusing, ultrasound echoesgenerated by reflection from the reflection points in directions otherthan the first direction are also received by the plural elements.Therefore, it is possible to visualize a reflector, such as a needle, byperforming second reception focusing according to the reflection on thepath in the second direction. In addition, it is also possible tovisualize the tissue by performing the reception focusing in the firstdirection. Therefore, it is possible to visualize a reflector, such as aneedle, without lowering the frame rate. That is, the present disclosuremay further include performing first reception focusing according toreflection on a path in the first direction, so that it is possible tovisualize the tissue while visualizing a reflector, such as a needle,without lowering the frame rate. In this case, results of the receptionfocusing of the first reception focusing and the second receptionfocusing may be combined.

In the second aspect, the ultrasound beam may be transmitted from theplural elements by forming a transmission focus in the first directionin each of two or more different openings of the probe, and receptionfocusing may be performed for the reception signal for each openingaccording to a common reflection point in the second direction in thesecond reception focusing.

In the second reception focusing, reception focusing may be performedbased on a delay time set on the assumption that each transmission waveconverges and diverges in a shape of a spherical wave in a shallowerregion and a deeper region than the transmission focus. In addition,specular reflection may be assumed at each point in the seconddirection, a sound source may be assumed at a different point from thepoint, and reception focusing may be performed for each point in thesecond direction based on a delay time for the assumed sound source.

The second aspect may further include determining a direction of aneedle based on a result of the second reception focusing.

In addition, a step of designating the second direction may be furtherincluded. In this case, the second direction may be designated based oninformation related to a direction obtained from a fixing portion thatfixes a needle. In addition, the second direction may be designatedbased on a result of the second reception focusing that has beenperformed last time.

A third aspect of the present disclosure is a non-transitory storagemedium storing an ultrasound diagnostic program that causes a computerto execute processing including: transmitting an ultrasound beam byforming a transmission focus in a predetermined first direction fromplural elements of a probe, the probe including the plural elements thatgenerate and transmit ultrasound waves and receive ultrasound wavesreflected from an inspection target; and performing second receptionfocusing for each reception signal received by each element of the probeaccording to reflection on a path in a second direction other than thefirst direction, among transmission wave paths of the ultrasound beamtransmitted into the inspection target.

According to the third aspect, ultrasound waves are transmitted from theplural elements of the probe, which includes the plural elements thatgenerate and transmit ultrasound waves and receive ultrasound wavesreflected from the inspection target, so as to transmit an ultrasoundbeam by forming a transmission focus in a first direction set inadvance.

In addition, the second reception focusing is performed for eachreception signal received by each element of the probe according to thereflection on the path in the second direction other than the firstdirection, among the transmission wave paths of the ultrasound beamtransmitted into the inspection target in the transmission step.

Thus, by performing the transmission focusing, ultrasound echoesgenerated by reflection from the reflection points in directions otherthan the first direction are also received by the plural elements.Therefore, it is possible to visualize a reflector, such as a needle, byperforming second reception focusing according to the reflection on thepath in the second direction. In addition, it is also possible tovisualize the tissue by performing the reception focusing in the firstdirection. Therefore, it is possible to visualize a reflector, such as aneedle, without lowering the frame rate. That is, the present disclosuremay further include performing first reception focusing according toreflection on a path in the first direction, so that it is possible tovisualize the tissue while visualizing a reflector, such as a needle,without lowering the frame rate. In this case, results of the receptionfocusing of the first reception focusing and the second receptionfocusing may be combined.

In the third aspect, the ultrasound beam may be transmitted from theplural elements by forming a transmission focus in the first directionin each of two or more different openings of the probe, and secondreception focusing may be performed for the reception signal for eachopening according to a common reflection point in the second direction.

In the second reception focusing, reception focusing may be performedbased on a delay time set on the assumption that each transmission waveconverges and diverges in a shape of a spherical wave in a shallowerregion and a deeper region than the transmission focus. In addition,specular reflection may be assumed at each point in the seconddirection, a sound source may be assumed at a different point from thepoint, and reception focusing may be performed for each point in thesecond direction based on a delay time for the assumed sound source.

The processing of the third aspect may further include determining adirection of a needle based on a result of the second receptionfocusing.

In addition, designating the second direction may be further included.In this case, the second direction may be designated based oninformation regarding a direction obtained from a fixing portion thatfixes a needle. In addition, the second direction may be designatedbased on a result of the second reception focusing that has beenperformed last time.

As described above, according to the present aspects, it is possible tovisualize a reflector, such as a needle, other than the tissue withoutlowering the frame rate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the schematic configuration of anultrasound diagnostic device according to a first embodiment of thepresent disclosure.

FIG. 2A is a diagram for explaining specular reflection by the needlefor each depth of the transmission focus, and is a diagram showing acase in which the transmission focus is shallower than the needle.

FIG. 2B is a diagram for explaining specular reflection by the needlefor each depth of the transmission focus, and is a diagram showing acase in which the transmission focus is deeper than the needle.

FIG. 2C is a diagram for explaining specular reflection by the needlefor each depth of the transmission focus, and is a diagram showing acase in which the transmission focus is located behind the opening.

FIG. 3A is a diagram showing an example of performing reception focusingaccording to the reflection on the path in a direction other than thetransmission beam direction, and is a diagram showing a case in whichthe transmission focus is shallower than the needle.

FIG. 3B is a diagram showing an example of performing reception focusingaccording to the reflection on the path in a direction other than thetransmission beam direction, and is a diagram showing a case in whichthe transmission focus is located behind the opening.

FIG. 4 is a block diagram showing the schematic configuration of aphasing addition/detection processing section in the ultrasounddiagnostic device according to the first embodiment of the presentdisclosure.

FIG. 5A is a diagram for explaining reception focusing performed by asecond reception focusing section in the ultrasound diagnostic deviceaccording to the first embodiment of the present disclosure.

FIG. 5B is a diagram for explaining reception focusing performed by thesecond reception focusing section in the ultrasound diagnostic deviceaccording to the first embodiment of the present disclosure.

FIG. 5C is a diagram for explaining reception focusing performed by thesecond reception focusing section in the ultrasound diagnostic deviceaccording to the first embodiment of the present disclosure.

FIG. 6 is a flowchart showing an example of the flow of the processperformed by the main part of the ultrasound diagnostic device accordingto the first embodiment of the present disclosure.

FIG. 7A is a diagram for explaining reception focusing performed by thesecond reception focusing section in the ultrasound diagnostic deviceaccording to the first embodiment of the present disclosure (when anacoustic wave equivalent to a case in which a sound source is present atthe symmetrical position with the needle as a specular reflectionsurface is taken into consideration).

FIG. 7B is a diagram for explaining reception focusing performed by thesecond reception focusing section in the ultrasound diagnostic deviceaccording to the first embodiment of the present disclosure (when anacoustic wave equivalent to a case in which a sound source is present atthe symmetrical position with the needle as a specular reflectionsurface is taken into consideration).

FIG. 8 is a diagram for explaining reception focusing in a θ directionusing the element signals of plural scanning lines, which is performedby a second reception focusing section in an ultrasound diagnosticdevice according to a second embodiment of the present disclosure.

FIG. 9A is a diagram for explaining reception focusing in a θ directionusing the element signals of plural scanning lines, which is performedby the second reception focusing section in the ultrasound diagnosticdevice according to the second embodiment of the present disclosure(when an acoustic wave equivalent to a case in which a sound source ispresent at the symmetrical position with the needle as a specularreflection surface is taken into consideration).

FIG. 9B is a diagram for explaining reception focusing in a θ directionusing the element signals of plural scanning lines, which is performedby the second reception focusing section in the ultrasound diagnosticdevice according to the second embodiment of the present disclosure(when an acoustic wave equivalent to a case in which a sound source ispresent at the symmetrical position with the needle as a specularreflection surface is taken into consideration).

FIG. 10 is a flowchart showing an example of the flow of the processperformed by the main part of the ultrasound diagnostic device 10according to the second embodiment of the present disclosure.

FIG. 11 is a diagram for explaining reception focusing performed by asecond reception focusing section in an ultrasound diagnostic deviceaccording to a third embodiment of the present disclosure.

FIG. 12A is a diagram for explaining reception focusing performed by thesecond reception focusing section in the ultrasound diagnostic deviceaccording to the third embodiment of the present disclosure (when anacoustic wave equivalent to a case in which a sound source is present atthe symmetrical position with the needle as a specular reflectionsurface is taken into consideration).

FIG. 12B is a diagram for explaining reception focusing performed by thesecond reception focusing section in the ultrasound diagnostic deviceaccording to the third embodiment of the present disclosure (when anacoustic wave equivalent to a case in which a sound source is present atthe symmetrical position with the needle as a specular reflectionsurface is taken into consideration).

FIG. 13 is a flowchart showing an example of the flow of the processperformed by the main part of the ultrasound diagnostic device accordingto the third embodiment of the present disclosure.

FIG. 14 is a flowchart showing an example of the flow of the processwhen generating the RF signal of one scanning line using one of elementreception signals that share the transmission focus in the ultrasounddiagnostic device according to the third embodiment of the presentdisclosure.

FIG. 15A is a diagram for explaining reception focusing performed by thesecond reception focusing section in the ultrasound diagnostic deviceaccording to the third embodiment of the present disclosure.

FIG. 15B is a diagram for explaining reception focusing performed by thesecond reception focusing section in the ultrasound diagnostic deviceaccording to the third embodiment of the present disclosure.

FIG. 16 is a diagram for explaining reception focusing performed by thesecond reception focusing section in the ultrasound diagnostic deviceaccording to the third embodiment of the present disclosure (when anacoustic wave equivalent to a case in which a sound source is present atthe symmetrical position with the needle as a specular reflectionsurface is taken into consideration).

FIG. 17A is a diagram for explaining a method of calculating DX2 and DY2in FIG. 16.

FIG. 17B is a diagram for explaining a method of calculating DX2 and DY2in FIG. 16.

FIG. 18A is a diagram showing a state in which the reflection of theneedle deviates from the reception opening.

FIG. 18B is a diagram showing an example of receiving the reflection bythe needle by transmitting the transmission beam so as to be inclined.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an example of an embodiment of the present disclosure willbe described with reference to the respective diagrams.

(First Embodiment)

FIG. 1 is a block diagram showing the schematic configuration of anultrasound diagnostic device according to a first embodiment of thepresent disclosure.

As shown in FIG. 1, an ultrasound diagnostic device 10 includes anultrasound probe 12, a transmission unit 14 and a receiving unit 16 thatare connected to the ultrasound probe 12, an A/D conversion unit 18, anelement data storage unit 20, an image generation unit 24, a displaycontrol unit 26, a display unit 28, a control unit 30, an operating unit32, and a storage unit 34.

The ultrasound probe 12 has a probe 36 that is used in a normalultrasound diagnostic device. The probe 36 includes plural elements,that is, ultrasound transducers arranged in a one-dimensional ortwo-dimensional array. When capturing an ultrasound image of a subject,each of the ultrasound transducers transmits an ultrasound beam to thesubject according to a driving signal supplied from the transmissionunit 14, and receives an ultrasound echo from the subject and outputs areception signal. In the present embodiment, each of a predeterminednumber of ultrasound transducers that form a set of the pluralultrasound transducers of the probe 36 generates each component of oneultrasound beam, and a set of a predetermined number of ultrasoundtransducers generates one ultrasound beam to be transmitted to thesubject.

For example, each ultrasound transducer is formed by an element(transducer) in which electrodes are formed at both ends of thepiezoelectric body including piezoelectric ceramic represented by leadzirconate titanate (PZT), a polymer piezoelectric element represented bypolyvinylidene fluoride (PVDF), piezoelectric single crystal representedby lead magnesium niobate-lead titanate (PMN-PT), or the like. That is,the probe 36 is a transducer array in which plural transducers arearranged in a one-dimensional or two-dimensional array as pluralultrasound elements.

When a pulsed or continuous-wave voltage is applied to the electrodes ofsuch a transducer, the piezoelectric body expands and contracts togenerate pulsed or continuous-wave ultrasound waves from eachtransducer. By combination of these ultrasound waves, an ultrasound beamis formed. In addition, the respective transducers expand and contractby receiving the propagating ultrasound waves, thereby generatingelectrical signals. These electrical signals are output as receptionsignals of the ultrasound waves.

The transmission unit 14 includes, for example, plural pulsers. Based ona transmission delay pattern selected according to the control signalfrom the control unit 30, the transmission unit 14 adjusts the amount ofdelay of the driving signal of each ultrasound element so that theultrasound beam components transmitted from plural ultrasoundtransducers (hereinafter, referred to as ultrasound elements) of theprobe 36 form one ultrasound beam, and supplies the adjusted drivingsignals to the plural ultrasound elements that form a set. Accordingly,ultrasound waves are transmitted from the plural ultrasound elements,transmission focusing is performed to generate an ultrasound beam, andthe ultrasound beam is transmitted.

According to the control signal from the control unit 30, the receivingunit 16 receives an ultrasound echo, which is generated by theinteraction between the ultrasound beam and the subject, from thesubject using each ultrasound element of the probe 36, amplifies thereception signal, that is, an analog element signal of each ultrasoundelement, and supplies the amplified analog element signal to the A/Dconversion unit 18.

The A/D conversion unit 18 is connected to the receiving unit 16, andconverts the analog element signal supplied from the receiving unit 16into digital element data. The A/D conversion unit 18 supplies theA/D-converted digital element data to the element data storage unit 20.

The element data storage unit 20 stores the digital element data outputfrom the A/D conversion unit 18 in a sequential manner. In addition, theelement data storage unit 20 stores information regarding the frame rateinput from the control unit 30 (for example, parameters indicating thedepth of the reflection position of an ultrasound wave, the density ofscanning lines, and a field-of-view width) so as to be associated withthe above digital element data (hereinafter, simply referred to aselement data).

Under the control of the control unit 30, the image generation unit 24generates an acoustic ray signal (reception data) from the element datastored in the element data storage unit 20, and generates an ultrasoundimage from the acoustic ray signal. Specifically, the image generationunit 24 includes a phasing addition/detection processing section 40, aDSC 42, an image generation section 44, and an image memory 46.

The phasing addition/detection processing section 40 performs receptionfocusing processing by selecting one reception delay pattern from pluralreception delay patterns stored in advance according to the receivingdirection set by the control unit 30, applying each delay to the elementdata based on the selected reception delay pattern, and adding up theresults. Through the reception focusing processing, reception data(acoustic ray signal) with a narrowed focus of the ultrasound echo isgenerated.

The phasing addition/detection processing section 40 generates B-modeimage data, which is tomographic image information regarding a tissuewithin the subject, by correcting the attenuation due to the distanceaccording to the depth of the reflection position of the ultrasound waveand then performing envelope detection processing for the reception datagenerated by the reception focusing processing.

The digital scan converter (DSC) 42 converts the B-mode image datagenerated by the detection processing section 40 into image dataaccording to the normal television signal scanning method (rasterconversion).

The image generation section 44 generates B-mode image data to besupplied for inspection or display by performing various kinds ofrequired image processing, such as gradation processing, on the B-modeimage data input from the DSC 42, and outputs the generated B-mode imagedata for inspection or display to the display control unit 26 in orderto display the generated B-mode image data or stores the generatedB-mode image data for inspection or display in the image memory 46.

The image memory 46 temporarily stores the B-mode image data forinspection generated by the image generation section 44. The B-modeimage data for inspection stored in the image memory 46 is read out tothe display control unit 26, when necessary, so as to be displayed onthe display unit 28.

The display control unit 26 displays an ultrasound image on the displayunit 28 based on the B-mode image signal for inspection having beensubjected to image processing by the image generation section 44.

The display unit 28 includes, for example, a display device, such as anLCD, and displays an ultrasound image under the control of the displaycontrol unit 26.

The control unit 30 controls each unit of the ultrasound diagnosticdevice 10 based on a command that is input from the operating unit 32 bythe operator.

When various kinds of information, especially, information required tocalculate the delay time used in the phasing addition/detectionprocessing section 40 of the image generation unit 24 has been inputthrough the operating unit 32 by the operator, the control unit 30supplies the above-described various kinds of information input throughthe operating unit 32 to the respective units, such as the transmissionunit 14, the receiving unit 16, the element data storage unit 20, theimage generation unit 24, and the display control unit 26, whennecessary.

The operating unit 32 is used when the operator performs an inputoperation, and includes a keyboard, a mouse, a trackball, a touch panel,and the like.

The operating unit 32 includes an input device used when the operatorinputs various kinds of information, especially, information regardingplural ultrasound elements of the probe 36 of the probe 12 used for thedelay time calculation described above, the speed of sound in aninspection target region of the subject, a focal position of theultrasound beam, and a transmission opening and a reception opening ofthe probe 36, when necessary.

The storage unit 34 stores various kinds of information input throughthe operating unit 32, especially, the above information regarding theprobe 12, the speed of sound, the focal position, and the transmissionopening and the reception opening, information required for theprocessing or operation of each unit controlled by the control unit 30,such as the transmission unit 14, the receiving unit 16, the elementdata storage unit 20, the image generation unit 24, and the displaycontrol unit 26, an operation program or a processing program forexecuting the processing or operation of each unit, and the like. As thestorage unit 34, recording media, such as a hard disk, a flexible disk,an MO, an MT, a RAM, a CD-ROM, and a DVD-ROM, can be used.

The phasing addition/detection processing section 40, the DSC 42, theimage generation section 44, and the display control unit 26 may beconfigured by a CPU and an operation program causing the CPU to performvarious kinds of processing, or a hardware configuration, such as adigital circuit, may be used therefor.

Incidentally, in the ultrasound diagnostic device 10 configured asdescribed above, the ultrasound beam is transmitted by performingtransmission focusing, and acoustic waves (ultrasound beams) formed bytransmission focusing propagate in various directions in a shallower ordeeper region than the transmission focus. Accordingly, even if thespecular reflection by the needle in the transmission beam directiondeviates from the reception opening, the specular reflection of acousticwaves in directions other than the transmission beam direction due tothe needle is captured in the reception opening, as shown by the one-dotchain line in FIGS. 2A to 2C. The reflection of the acoustic wave, whichis formed by transmission focusing, by the needle is equivalent to acase in which there is a focus at the symmetrical position of the focusformed by transmission focusing with the needle as a specular reflectionsurface. Therefore, if the transmission focus is regarded as a pseudosound source, as shown in FIGS. 2A and 2C, reflection equivalent to theacoustic wave when a pseudo sound source is present at the symmetricalposition of the transmission focus with respect to the needle is caughtin the reception opening. In the case shown in FIG. 2B, a sound sourceis actually formed. However, since the reflection spread range isdetermined by the directivity of an element, transmission opening,depth, frequency, or the like, the reflection does not necessarilyspread in all directions. Accordingly, the above-described pseudo soundsource or the reflected wave equivalent to the sound source cannotnecessarily be captured. That is, the spread range of the acoustic wavein a shallower or deeper region than the transmission focus isdetermined by the transmission opening, depth, frequency, or the like,and reflection spreads only to a range interposed in the direction ofspecular reflection by the needle in a direction at both the ends. Thespecular reflection in the transmission beam direction can be regardedas a part of the reflection.

Therefore, in the ultrasound diagnostic device 10 according to thepresent embodiment, focusing on the fact that the acoustic wave of theultrasound beam formed by transmission focusing also propagates indirections other than the transmission beam direction, the reflector,such as a needle, other than the tissue can be satisfactorily visualizedby performing reception focusing for each reception signal, which isreceived by each ultrasound element of the probe 36, according to thereflection on the path in a direction other than the transmission beamdirection, as shown in FIGS. 3A and 3B. In the present embodiment, thereception focusing is performed based on the delay time set on theassumption that transmission waves converge and diverge in the shape ofa spherical wave in a shallower region and a deeper region than thetransmission focus.

In the present embodiment, the phasing addition/detection processingsection 40 is configured to perform the reception focusing according tothe reflection on the path in a direction other than the transmissionbeam direction. FIG. 4 is a block diagram showing the schematicconfiguration of the phasing addition/detection processing section 40 inthe ultrasound diagnostic device 10 according to the first embodiment ofthe present disclosure.

Specifically, as shown in FIG. 4, the phasing addition/detectionprocessing section 40 includes a first reception focusing section 40A, asecond reception focusing section 40B, a first detection processingsection 40C, a second detection processing section 40D, and acombination processing section 40E.

The first reception focusing section 40A performs reception focusing byselecting one reception delay pattern from plural reception delaypatterns stored in advance for the transmission direction (verticaldirection in the present embodiment) of the ultrasound beam, applyingeach delay to the element data based on the selected reception delaypattern, and adding up the results.

The second reception focusing section 40B performs reception focusing soas to be inclined by the angle θ from the transmission focus withrespect to the transmission direction (vertical direction) of theultrasound beam.

Here, a reception focus that is inclined by the angle θ with respect tothe transmission direction will be described with reference to FIGS. 5Ato 5C.

As shown in FIG. 5A, when the transmission beam is vertical, the depthof the reflection point is given by V×T0/2. The depth of the reflectionpoint in a direction inclined by θ with respect to the verticaldirection is also given by V×T0/2. Here, T0 indicates a reciprocatingultrasound wave propagation time in a vertical direction or in adirection inclined by θ with respect to the vertical direction, and Vindicates the speed of sound.

Then, it can be seen from FIG. 5B that the distances DX and DY of thereflection point from the transmission focus in the θ direction aregiven by the following equations. Here, FD indicates the depth of thetransmission focus.DX=(V×Tt−FD)×sin(θ)DY=(V×Tt−FD)×cos(θ)Tt=T0/2

Then, it can be seen from FIG. 5C that the distances X and Y of thereflection point from the j-th element from the center of the openingare given by the following equations.X=DX−j×EPY=DY+FD

Here, EP is a gap between elements, and j is a positive or negativevalue with an element at the center as 0.

Therefore, it can be seen that the propagation time of the acoustic wavereturning to the j-th element from the reflection point is given by thefollowing equation.Tr=sqrt(X ² +Y ²)/V

The ultrasound wave transmitted from the opening is reflected at thereflection point after Tt, and returns to the j-th element after Tr.That is, the reflected wave from the reflection point returns to thej-th element after T=Tt+Tr from the transmission.

Therefore, by adding up the signals of the respective elements using thefollowing equation, it is possible to extract the reflected wave fromthe reflection point, that is, it is possible to perform receptionfocusing.RF(i, T0)=ΣELE(i, j, T)

Here, i indicates a scanning line to which the opening corresponds,ELE(i, j, T) indicates a signal at time T of an element j of thescanning line i, and RF(i, T0) indicates an RF signal at time T0(equivalent to depth) in the θ direction of the scanning line i afterreception focusing.

That is, reception focusing that is inclined by the angle θ with respectto the transmission direction is performed so as to satisfy thefollowing equations.RF(i, T0)=ΣELE(i, j, T)T=Tt+TrTr=sqrt(X ² +Y ²)/VX=DX−j×EPY=DY+FDDX=(V×Tt−FD)×sin(θ)DY=(V×Tt−FD)×cos(θ)Tt=T0/2

Here, RF(i, T0): RF signal of the i-th scanning line at time T0. Thetime of the moment of transmission is set to 0.

ELE(i, j, T): data at time T of the j-th element of the element signalacquired by transmission corresponding to the i-th scanning line. Here,j is 0 in the case of an element corresponding to the i-th scanning lineposition, and is a positive or negative value.

Σ: integration on j

Tt: time until the transmission wave reaches a reflection point

Tr: time until the reflected wave reaches an element

V: speed of sound

EP: gap between elements

FD: depth of transmission focus

θ: angle of the reception focusing direction that is inclined withrespect to the transmission direction

As shown in FIG. 3B, when forming a transmission focus behind thetransmission opening, the depth FD of the transmission focus isnegative.

On the other hand, the first detection processing section 40C generatesB-mode image data, which is tomographic image information regarding atissue within the subject, by correcting the attenuation due to thedistance according to the depth of the reflection position of theultrasound wave and then performing envelope detection processing forthe reception data generated by the first reception focusing section40A.

Similarly, the second detection processing section 40D generates B-modeimage data, which is image information regarding a reflector, such as aneedle, by correcting the attenuation due to the distance according tothe depth of the reflection position of the ultrasound wave and thenperforming envelope detection processing for the reception datagenerated by the second reception focusing section 40B.

Then, the combination processing section 40E performs processing forcombining the B-mode image data (image A) generated by the firstdetection processing section 40C and the B-mode image data (image B)generated by the second detection processing section 40D. Specifically,since RF(i, T0) generated by the above-described equation is inclined bythe angle θ with respect to the vertical direction, coordinatetransformation (scan conversion) is performed so as to match thecoordinates of the image A and the image B and the image A and the imageB are added up in a predetermined ratio to generate a display image. Inthis case, the processing may be performed by performing gradationconversion for emphasis as many as the number of high-brightness pixelsof the image B, or by extracting only the high-brightness pixels as aneedle, or by extracting only the pixels in a predetermined range, or bydetecting a straight line by the Hough transform or the like andextracting only the pixels around the detected straight line. Inaddition, processing for color conversion, chroma conversion, or thelike may be further performed according to the brightness of the image Aand the image B.

Here, even if the direction of the reception focus by the secondreception focusing section 40B is not necessarily perpendicular to theneedle, it is possible to visualize the needle as long as the directionof specular reflection by the needle in the direction of the receptionfocus does deviate from the reception opening. That is, since thespecular reflection from the needle is a result of integrating thereflection from each point on the needle, it is possible to capture andvisualize a part of specular reflection by the needle by the receptionfocusing according to the reflection point on the needle as long as theintegration result is not zero (specular reflection does not deviatefrom the reception opening). This is the same as the reason thatextraction is possible even if the needle is not horizontal in theultrasound image generated with both the transmission beam direction andthe reception beam direction as vertical directions.

The reception focusing direction of each of the first reception focusingsection 40A and the second reception focusing section 40B may bedesignated by operating the operating unit 32 or the like, or may bedesignated by acquiring information regarding a direction obtained fromthe jig for fixing the needle. Alternatively, a current receptionfocusing direction may be designated based on the result of the lastreception focusing.

Subsequently, the operation of the ultrasound diagnostic device 10according to the first embodiment of the present disclosure and a methodof generating an ultrasound image will be described.

FIG. 6 is a flowchart showing an example of the flow of the processperformed by the main part of the ultrasound diagnostic device 10according to the first embodiment of the present disclosure.

In step 100, a scanning line n is reset (n=0), and the process proceedsto step 102. In step 102, the scanning line n is incremented by 1(n=n+1), and the process proceeds to step 104.

In step 104, transmission focusing is performed to acquire each elementreception signal, and the process proceeds to step 106. That is, whenthe operator brings the ultrasound probe 12 into contact with thesurface of the subject to start measurement, an ultrasound beam istransmitted from the probe 36 according to the driving signal suppliedfrom the transmission unit 14. Then, the ultrasound echo generated byinteraction between the transmitted ultrasound beam and the subject isreceived by the probe 36, the analog element signal is amplified by thereceiving unit 16, the amplified analog element signal is converted intodigital element data by the A/D conversion unit 18, and the digitalelement data is stored in the element data storage unit 20.

In step 106, the image A for tissue imaging is generated by performingreception focusing in the same direction as the transmission beam forthe reception signal of each element, and the process proceeds to step108. That is, the first reception focusing section 40A acquires eachelement reception signal from the element data storage unit 20 andgenerates reception data (acoustic ray signal) by performing receptionfocusing in the vertical direction, and the first detection processingsection 40C generates a B-mode image signal of the image A for tissueimaging by processing the acoustic ray signal.

In step 108, the image B for needle imaging is generated by performingreception focusing in a direction, which is inclined by the angle θ withrespect to the transmission beam, for the reception signal of eachelement, and the process proceeds to step 110. That is, the secondreception focusing section 40B acquires each element reception signalfrom the element data storage unit 20 and generates reception data(acoustic ray signal) by performing reception focusing in a directionthat is inclined by the angle θ with respect to the vertical direction,and the second detection processing section 40D generates a B-mode imagesignal of the image B for needle imaging by processing the acoustic raysignal.

In step 110, it is determined whether or not n=N. That is, it isdetermined whether or not the above processing has ended for all thescanning lines. When the determination is negative, the process proceedsto step 102 to repeat the above processing. When the determination ispositive, the process proceeds to step 112.

In step 112, the combination processing section 40E generates a displayimage of one frame by combining the image A and the image B, which havebeen generated as described above, by scan conversion, and the series ofprocesses are ended. A display image of the next frame is generated byperforming the process from the processing of step 100.

Thus, the ultrasound diagnostic device 10 according to the firstembodiment of the present disclosure generates an ultrasound beam byperforming transmission focusing, receives an ultrasound signal,generates an image for tissue imaging by performing reception focusingin the transmission direction, and generates an image for reflector(needle) imaging other than the tissue by performing reception focusingin a different direction from the transmission direction. Therefore, itis possible to visualize a reflector other than the tissue by oneultrasound transmission.

In the first embodiment described above, the second reception focusingsection 40B performs reception focusing in a direction that is inclinedby the angle θ with respect to the vertical direction. As shown in FIGS.2A to 2C, in consideration of the fact that the reflected wave from theneedle becomes an acoustic wave equivalent to a case in which a soundsource is present at the symmetrical position with the needle as aspecular reflection surface, the reception focusing may be performed.

Here, a case in which reception focusing is performed in considerationof the fact that the reflected wave from the needle becomes an acousticwave equivalent to a case in which a sound source is present at thesymmetrical position with the needle as a specular reflection surfacewill be described with reference to FIGS. 7A and 7B.

First, calculating DX and DY from FIG. 7A using the following equationsis the same as that described above.DX=(V×Tt−FD)×sin(θ)DY=(V×Tt−FD)×cos(θ)Tt=T0/2

Then, as shown in FIG. 7B, a needle passing through the reflection pointis assumed, and a pseudo sound source is assumed at the symmetricalposition of the transmission focus. Distances DX2 and DY2 from thetransmission focus to the sound source are given by the followingequations.DX2=2×DXDY2=2×DY

Distances X and Y of the sound source from the j-th element are given bythe following equations.X=DX2−j×EPY=DY2+FD

The propagation time of the acoustic wave returning to the j-th elementfrom the sound source is given by the following equation.Tr=sqrt(X ² +Y ²)/V

Time until the transmission focus is formed from the transmission of theultrasound wave from the opening is FD/V, and it is thought thatpropagation from the pseudo sound source to the j-th element starts atthat moment. Accordingly, it is thought that the reflected wave from thereflection point returns to the j-th element after T=FD/V+Tr from thetransmission of the ultrasound wave from the opening.

Therefore, by adding up the signals of the respective elements using thefollowing equation, it is possible to extract the reflected wave fromthe reflection point, that is, it is possible to perform receptionfocusing.RF(i, T0)=ΣELE(i, j, T)

That is, when performing reception focusing in consideration of the factthat the reflected wave from the needle becomes an acoustic waveequivalent to a case in which a sound source is present at thesymmetrical position with the needle as a specular reflection surface,the reception focusing is performed so as to satisfy the followingequations.RF(i, T0)=ΣELE(i, j, T)T=FD/V+TrTr=sqrt(X ² +Y ²)/VX=DX2−j×EPY=DY2+FDDX2=2×DXDY2=2×DYDX=(V×Tt−FD)×sin(θ)DY=(V×Tt−FD)×cos(θ)Tt=T0/2

The difference from the equations of the reception focusing in thesecond reception focusing section 40B of the first embodiment describedabove is that a needle passing through the reflection point in avertical direction with the angle θ is assumed, a sound source of DX2and DY2 is assumed as a symmetrical position of the transmission focuswith respect to the needle, and the time of propagation to each elementfrom the assumed sound source is calculated and that the time FD/V untilthe transmission focus is formed is added by regarding the assumed soundsource as being formed at the same time as the formation of thetransmission focus.

By performing the reception focusing in this manner, it is possible toperform the reception focusing according to the specular reflection fromthe needle. Therefore, it is possible to visualize the needle betterthan in the first embodiment. However, by performing reception focusingaccording to the specular reflection, which is an integration resultincluding ambient reflection, as well as the focused reflection, thereception focusing is also performed on the ambient reflection.Accordingly, even if the focused reflection deviates from the point onthe needle, the needle is visualized if the point on the needle isincluded in the ambient reflection. As a result, the visualizationperformance of the needle tip is reduced compared with that in the firstembodiment.

(Second Embodiment)

Subsequently, an ultrasound diagnostic device according to a secondembodiment of the present disclosure will be described. Since the basicconfiguration is the same as that in the first embodiment, the detailedexplanation thereof will be omitted and the differences will bedescribed.

In the first embodiment, in order to generate an RF signal of onescanning line in a direction that is inclined by the angle θ, one ofelement reception signals that share the transmission focus is used. Inthe second embodiment, an example will be described in which not onlyeach of element reception signals that share the transmission focus butalso plural element reception signals including the periphery are usedin order to generate the RF signal of one scanning line.

That is, in the second embodiment, the transmission unit 14 transmitsultrasound waves from plural ultrasound elements so as to transmit anultrasound beam by forming a transmission focus in a first direction ineach of two or more different openings of the probe 36. When generatingreception data (acoustic ray signal) by performing reception focusing ina direction, which is inclined by the angle θ with respect to thevertical direction, using element data obtained by an element dataprocessing unit 22, the second reception focusing section 40B performsreception focusing using the element reception signals of pluralscanning lines.

Here, reception focusing in the θ direction using the element signals ofplural scanning lines will be described with reference to FIG. 8.

First, a method in which specular reflection is not assumed will bedescribed with reference to FIG. 8.

Distances DX and DY of the reflection point in the θ direction of thescanning line i from the transmission focus are given by the followingequations as described above.DX=(V×Tt−FD)×sin(θ)DY=(V×Tt−FD)×cos(θ)Tt=T0/2

Then, the distance of the reflection point from the transmission focusof the scanning line (i+k) is calculated.

Since the scanning line (i+k) is spaced apart from the scanning line iby k×EP, DX2 is expressed as follows.DX2=DX−k×EP

Here, k is a positive or negative value with the i-th scanning line as0.

In addition, the distance is given as follows.sign(DY)×sqrt(DX2² +DY ²)

Here, when DY is negative, sign(DY) is also multiplied in order to setthe distance to a negative value.

It can be seen that the time until the acoustic wave transmitted fromthe opening of the scanning line (i+k) reaches the reflection point isas follows.Tt2=(FD+sign(DY)×sqrt(DX2² +DY ²))/V

On the other hand, it can be seen that the propagation time of theacoustic wave, which returns from the reflection point to the j-thelement (has a positive or negative value with an element correspondingto the position of the scanning line (i+k) as 0) of the opening of thescanning line (i+k), is as follows.Tr=sqrt(X ² +Y ²)/V

Here, X=DX−(k+j)×EP, and Y=DY+FD.

Therefore, by adding up the signals of the respective elements of eachscanning line using the following equations, it is possible to extractthe reflected wave from the reflection point, that is, it is possible toperform reception focusing.RF(i, T0)=ΣΣELE(i+k, j, T)T=Tt2+Tr

Here, i+k indicates a scanning line, j indicates an element, one of twoΣ indicates integration on k, and the other Σ indicates integration onj.

That is, reception focusing in the θ direction using the element signalsof plural scanning lines (method in which specular reflection is notassumed) is performed so as to satisfy the following equations.RF(i, T0)=ΣΣELE(i+k, j, T)T=Tt2+TrTr=sqrt(X ² +Y ²)/VX=DX−(k+j)×EPY=DY+FDTt2=(FD+sign(DY)×sqrt(DX2² +DY ²))/VDX2=DX−k×EPDX=(V×Tt−FD)×sin(θ)DY=(V×Tt−FD)×cos(θ)Tt=T0/2

By performing reception focusing using the element reception signals ofplural scanning lines as described above, it is possible to improve thevisualization of a reflector, such as a needle, other than the tissue,compared with the first embodiment.

Next, a case in which reception focusing is performed in considerationof the fact that the reflected wave from the needle becomes an acousticwave equivalent to a case in which a sound source is present at thesymmetrical position with the needle as a specular reflection surfacewill be described with reference to FIGS. 9A and 9B.

First, distances DX and DY of the reflection point in the θ direction ofthe scanning line i from the transmission focus are given by thefollowing equations as described above (FIG. 9A).DX=(V×Tt−FD)×sin(θ)DY=(V×Tt−FD)×cos(θ)Tt=T0/2

Then, a pseudo sound source is assumed at the symmetrical position ofthe transmission focus of the scanning line i+k with respect to theneedle, and distances DX3 and DY3 from the transmission focus of thescanning line i+k to the pseudo sound source are calculated.

First, it can be seen that DX2 in FIG. 9B is given by the followingequation (here, k is a positive or negative value with the i-th scanningline as 0).DX2=DX−k×EP×sin(θ)×sin(θ)

In addition, it can be seen that DY2 is given by the following equation.DY2=DY−k×EP×sin(θ)×cos(θ)

Since DX3 and DY3 are values obtained by doubling DX2 and DY2, DX3 andDY3 are expressed as follows.DX3=2×DX2DY3=2×DY2

If DX3 and DY3 are known, it can be seen that the propagation time ofthe acoustic wave, which returns from the sound source to the j-thelement (has a positive or negative value with an element correspondingto the position of the scanning line (i+k) as 0) of the opening of thescanning line (i+k), is as follows.Tr=sqrt(X ² +Y ²)/V

Here, X=DX3−j×EP, and Y=DY3+FD.

Therefore, by adding up the signals of the respective elements of eachscanning line using the following equations, it is possible to extractthe reflected wave from the reflection point, that is, it is possible toperform reception focusing.RF(i, T0)=ΣΣELE(i+k, j, T)T=FD/V+Tr

Here, i+k indicates a scanning line, j indicates an element, one of twoΣ indicates integration on k, and the other Σ indicates integration onj.

That is, reception focusing in the second reception focusing section 40Bis performed so as to satisfy the following equations.RF(i, T0)=ΣΣELE(i+k, j, T)T=FD/V+TrTr=sqrt(X ² +Y ²)/VX=DX3−j×EPY=DY3+FDDX3=2×DX2DY3=2×DY2DX2=DX−k×EP×sin(θ)×sin(θ)DY2=DY−k×EP×sin(θ)×cos(θ)DX=(V×Tt−FD)×sin(θ)DY=(V×Tt−FD)×cos(θ)Tt=T0/2

Subsequently, the operation of the ultrasound diagnostic deviceaccording to the second embodiment of the present disclosure and amethod of generating an ultrasound image will be described.

FIG. 10 is a flowchart showing an example of the flow of the processperformed by the main part of the ultrasound diagnostic device 10according to the second embodiment of the present disclosure.

In step 200, a scanning line n is reset (n=0), and the process proceedsto step 202. In step 202, the scanning line n is incremented by 1(n=n+1), and the process proceeds to step 204.

In step 204, transmission focusing is performed to acquire each elementreception signal, and the process proceeds to step 206. That is, whenthe operator brings the ultrasound probe 12 into contact with thesurface of the subject to start measurement, an ultrasound beam istransmitted from the probe 36 according to the driving signal suppliedfrom the transmission unit 14. Then, the ultrasound echo generated byinteraction between the transmitted ultrasound beam and the subject isreceived by the probe 36, the analog element signal is amplified by thereceiving unit 16, the amplified analog element signal is converted intodigital element data by the A/D conversion unit 18, and the digitalelement data is stored in the element data storage unit 20.

In step 206, it is determined whether or not n=N. That is, it isdetermined whether or not the above processing has ended for all thescanning lines. When the determination is negative, the process returnsto step 202 to repeat the above processing. When the determination ispositive, the process proceeds to step 208.

In step 208, a scanning line n is reset (n=0), and the process proceedsto step 210. In step 210, the scanning line n is incremented by 1(n=n+1), and the process proceeds to step 212.

In step 212, the image A for tissue imaging is generated by performingreception focusing in the same direction as the transmission beam foreach element reception signal, and the process proceeds to step 214.That is, the first reception focusing section 40A acquires each elementreception signal from the element data storage unit 20 and generatesreception data (acoustic ray signal) by performing reception focusing inthe vertical direction, and the first detection processing section 40Cgenerates a B-mode image signal of the image A for tissue imaging byprocessing the acoustic ray signal.

In step 214, the image B for needle imaging is generated by performingreception focusing in a direction, which is inclined by the angle θ withrespect to the transmission beam, for each element reception signal, andthe process proceeds to step 216. That is, the second reception focusingsection 40B acquires each element reception signal from the element datastorage unit 20 and generates reception data (acoustic ray signal) byperforming reception focusing in a direction that is inclined by theangle θ with respect to the vertical direction, and the second detectionprocessing section 40D generates a B-mode image signal of the image Bfor needle imaging by processing the acoustic ray signal.

In step 216, it is determined whether or not n=N. That is, it isdetermined whether or not the above processing has ended for all thescanning lines. When the determination is negative, the process returnsto step 210 to repeat the above processing. When the determination ispositive, the process proceeds to step 218.

In step 218, the combination processing section 40E generates a displayimage of one frame by combining the image A and the image B, which havebeen generated as described above, by scan conversion, and the series ofprocesses are ended. A display image of the next frame is generated byperforming the process from the processing of step 200.

By performing such processing, reception focusing using the elementreception signals of plural scanning lines becomes possible. Therefore,it is possible to improve the performance of visualizing a reflector,such as a needle, other than the tissue, compared with the firstembodiment.

(Third Embodiment)

Subsequently, an ultrasound diagnostic device according to a thirdembodiment of the present disclosure will be described.

The reflection wave from the needle becomes an acoustic wave equivalentto a case in which a sound source is present at the symmetrical positionwith the needle as a specular reflection surface. However, since therange is determined and limited by the transmission opening, depth,frequency, and the like, the needle may not be able to be visualized ineach of the embodiments described above in the case of an acute angle.

Therefore, in the present embodiment, the transmission beam direction isinclined so as to be almost perpendicular to the needle, and then thetransmission beam is further inclined to perform reception focusing.

The basic configuration is the same as those in the first and secondembodiments, and only the processes are different. Accordingly, only thedifferences will be described.

In the ultrasound diagnostic device according to the third embodiment,the transmission beam is inclined. Accordingly, reception focusing bythe second reception focusing section 40B is performed as follows.

First, a case in which specular reflection is not assumed will bedescribed with reference to FIG. 11.

Assuming that the scanning line i is inclined by the angle ϕ, distancesDX and DY of the reflection point in a direction, which is furtherinclined by the angle θ, from the transmission focus are given by thefollowing equations.DX=(V×Tt−FD)×sin(ϕ+θ)DY=(V×Tt−FD)×cos(ϕ+θ)Tt=T0/2

Then, the distance of the reflection point from the transmission focusof the scanning line (i+k) is calculated.

Since the scanning line (i+k) is spaced apart from the scanning line iby k×EP, DX2 is expressed as follows.DX2=DX−k×EP

In addition, the distance is given as follows.sign(DY)×sqrt(DX2² +DY ²)

Here, when DY is negative, sign(DY) is also multiplied in order to setthe distance to a negative value.

It can be seen that the time until the acoustic wave transmitted fromthe opening of the scanning line (i+k) reaches the reflection point isas follows.Tt2=(FD+sign(DY)×sqrt(DX2² +DY ²))/V

On the other hand, it can be seen that the propagation time of theacoustic wave, which returns from the reflection point to the j-thelement (has a positive or negative value with an element correspondingto the position of the scanning line (i+k) as 0) of the opening of thescanning line (i+k), is as follows.Tr=sqrt(X ² +Y ²)/V

Here, X=DX+FD×sin(ϕ)−(k+j)×EP, and Y=DY+FD×cos(ϕ).

Therefore, by adding up the signals of the respective elements of eachscanning line using the following equations, it is possible to extractthe reflected wave from the reflection point, that is, it is possible toperform reception focusing.RF(i, T0)=ΣΣELE(i+k, j, T)T=Tt2+Tr

Here, i+k indicates a scanning line, j indicates an element, one of twoΣ indicates integration on k, and the other Σ indicates integration onj.

That is, when performing reception focusing in a direction that isfurther inclined by the angle θ with respect to the transmission beaminclined by the angle ϕ, reception focusing by the second receptionfocusing section 40B is performed so as to satisfy the followingequations.RF(i, T0)=ΣΣELE(i+k, j, T)T=Tt2+TrTr=sqrt(X ² +Y ²)/VX=DX+FD×sin(ϕ)−(k+j)×EPY=DY+FD×cos(ϕ)Tt2=(FD+sign(DY)×sqrt(DX2² +DY ²))/VDX2=DX−k×EPDX=(V×Tt−FD)×sin(ϕ+θ)DY=(V×Tt−FD)×cos(ϕ+θ)Tt=T0/2

In addition, if integration on k is not performed, one of elementreception signals that share the transmission focus is used.

Next, a case in which reception focusing is performed in considerationof the fact that the reflected wave from the needle becomes an acousticwave equivalent to a case in which a sound source is present at thesymmetrical position with the needle as a specular reflection surfacewill be described with reference to FIGS. 12A and 12B.

Assuming that the scanning line i is inclined by the angle ϕ, distancesDX and DY of the reflection point in a direction, which is furtherinclined by the angle θ, from the transmission focus are given by thefollowing equations (FIG. 12A).DX=(V×Tt−FD)×sin(ϕ+θ)DY=(V×Tt−FD)×cos(ϕ+θ)Tt=T0/2

Then, a pseudo sound source is assumed at the symmetrical position ofthe transmission focus of the scanning line i+k with respect to theneedle, and distances DX3 and DY3 from the transmission focus of thescanning line i+k to the pseudo sound source are calculated.

For the above, first, DX2 and DY2 are calculated in FIG. 12B. It can beseen that DX2 and DY2 are given by the following equations (here, k is apositive or negative value with the i-th scanning line as 0).DX2=DX−k×EP×sin(ϕ+θ)×sin(ϕ+θ)DY2=DY−k×EP×sin(ϕ+θ)×cos(ϕ+θ)

Since DX3 and DY3 are values obtained by doubling DX2 and DY2, DX3 andDY3 are expressed as follows.DX3=2×DX2DY3=2×DY2

If DX3 and DY3 are known, it can be seen that the propagation time ofthe acoustic wave, which returns from the sound source to the j-thelement (has a positive or negative value with an element correspondingto the position of the scanning line (i+k) as 0) of the opening of thescanning line (i+k), is as follows.Tr=sqrt(X ² +Y ²)/V

Here, X=DX3+FD×sin(ϕ)−j×EP, and Y=DY3+FD×cos(ϕ).

Therefore, by adding up the signals of the respective elements of eachscanning line using the following equations, it is possible to extractthe reflected wave from the reflection point, that is, it is possible toperform reception focusing.RF(i, T0)=ΣΣELE(i+k, j, T)T=FD/V +Tr

Here, i+k indicates a scanning line, j indicates an element, one of twoΣ indicates integration on k, and the other Σ indicates integration onj.

That is, when performing reception focusing in a direction, which isfurther inclined by the angle θ with respect to the transmission beaminclined by the angle ϕ, in consideration of the fact that the reflectedwave from the needle becomes an acoustic wave equivalent to a case inwhich a sound source is present at the symmetrical position with theneedle as a specular reflection surface, the second reception focusingsection 40B performs reception focusing so as to satisfy the followingequations.RF(i, T0)=ΣΣELE(i+k, j, T)T=FD/V+TrTr=sqrt(X ² +Y ²)/VX=DX3+FD×sin(ϕ)−j×EPY=DY3+FD×cos(ϕ)DX3=2×DX2DY3=2×DY2DX2=DX−k×EP×sin(ϕ+θ)×sin(ϕ+θ)DY2=DY−k×EP×sin(ϕ+θ)×cos(ϕ+θ)DX=(V×Tt−FD)×sin(ϕ+θ)DY=(V×Tt−FD)×cos(ϕ+θ)Tt=T0/2

In addition, if integration on k is not performed, one of elementreception signals that share the transmission focus is used.

FIG. 13 is a flowchart showing an example of the flow of the processperformed by the main part of the ultrasound diagnostic device accordingto the third embodiment of the present disclosure. The same processingas in the second embodiment will be described using the same referencenumerals.

In step 200, a scanning line n is reset (n=0), and the process proceedsto step 202. In step 202, the scanning line n is incremented by 1(n=n+1), and the process proceeds to step 203.

In step 203, transmission focusing is performed without tilting thetransmission beam to acquire each element reception signal, and theprocess proceeds to step 205. That is, when the operator brings theultrasound probe 12 into contact with the surface of the subject tostart measurement, an ultrasound beam is transmitted from the probe 36according to the driving signal supplied from the transmission unit 14.Then, the ultrasound echo generated by interaction between thetransmitted ultrasound beam and the subject is received by the probe 36,the analog element signal is amplified by the receiving unit 16, theamplified analog element signal is converted into digital element databy the A/D conversion unit 18, and the digital element data is stored inthe element data storage unit 20.

In step 205, transmission focusing is performed by tilting thetransmission beam to acquire each element reception signal, and theprocess proceeds to step 206. That is, according to the driving signalsupplied from the transmission unit 14, an ultrasound beam istransmitted from the probe 36. In this case, unlike in step 203, thetransmission beam is transmitted so as to be inclined. Then, theultrasound echo generated by interaction between the transmittedultrasound beam and the subject is received by the probe 36, the analogelement signal is amplified by the receiving unit 16, the amplifiedanalog element signal is converted into digital element data by the A/Dconversion unit 18, and the digital element data is stored in theelement data storage unit 20.

In step 206, it is determined whether or not n=N. That is, it isdetermined whether or not the above processing has ended for all thescanning lines. When the determination is negative, the process returnsto step 202 to repeat the above processing. When the determination ispositive, the process proceeds to step 208.

In step 208, a scanning line n is reset (n=0), and the process proceedsto step 210. In step 210, the scanning line n is incremented by 1(n=n+1), and the process proceeds to step 213.

In step 213, the image A for tissue imaging is generated by performingreception focusing in the same direction as the transmission beam foreach element reception signal acquired without tilting the transmissionbeam, and the process proceeds to step 215. That is, the first receptionfocusing section 40 A acquires each element reception signal acquired instep 203 from the element data storage unit 20 and generates receptiondata (acoustic ray signal) by performing reception focusing in thevertical direction, and the first detection processing section 40Cgenerates a B-mode image signal of the image A for tissue imaging byprocessing the acoustic ray signal.

In step 215, the image B for needle imaging is generated by performingreception focusing in a direction, which is inclined by the angle θ withrespect to the transmission beam, for each element reception signalacquired by tilting the transmission beam, and the process proceeds tostep 216. That is, the second reception focusing section 40B acquireseach element reception signal acquired in step 205 from the element datastorage unit 20 and generates reception data (acoustic ray signal) byperforming reception focusing in a direction that is further inclined bythe angle θ with respect to the transmission beam, and the seconddetection processing section 40D generates a B-mode image signal of theimage B for needle imaging by processing the acoustic ray signal.

In step 216, it is determined whether or not n=N. That is, it isdetermined whether or not the above processing has ended for all thescanning lines. When the determination is negative, the process returnsto step 210 to repeat the above processing. When the determination ispositive, the process proceeds to step 218.

In step 218, the combination processing section 40E generates a displayimage of one frame by combining the image A and the image B, which havebeen generated as described above, by scan conversion, and the series ofprocesses are ended. A display image of the next frame is generated byperforming the process from the processing of step 200.

In FIG. 13, the case has been described in which the RF signal of onescanning line is generated using the element reception signals of pluralscanning lines. However, when one of the element reception signals thatshare the transmission focus is used in order to generate the RF signalof one scanning line as in the first embodiment, processing shown inFIG. 14 may be performed instead of FIG. 13.

FIG. 14 is a flowchart showing an example of the flow of the processwhen generating the RF signal of one scanning line using one of theelement reception signals that share the transmission focus in theultrasound diagnostic device according to the third embodiment of thepresent disclosure. The same processing as in the first embodiment willbe described using the same reference numerals.

In step 100, a scanning line n is reset (n=0), and the process proceedsto step 102. In step 102, the scanning line n is incremented by 1(n=n+1), and the process proceeds to step 103.

In step 103, transmission focusing is performed in the verticaldirection without tilting the transmission beam to acquire each elementreception signal, and the process proceeds to step 106. That is, whenthe operator brings the ultrasound probe 12 into contact with thesurface of the subject to start measurement, an ultrasound beam istransmitted from the probe 36 according to the driving signal suppliedfrom the transmission unit 14. Then, the ultrasound echo generated byinteraction between the transmitted ultrasound beam and the subject isreceived by the probe 36, the analog element signal is amplified by thereceiving unit 16, the amplified analog element signal is converted intodigital element data by the A/D conversion unit 18, and the digitalconversion element data is stored in the element data storage unit 20.

In step 106, the image A for tissue imaging is generated by performingreception focusing in the same direction as the transmission beam forthe reception signal of each element, and the process proceeds to step107. That is, the first reception focusing section 40A acquires eachelement reception signal from the element data storage unit 20 andgenerates reception data (acoustic ray signal) by performing receptionfocusing in the vertical direction, and the first detection processingsection 40C generates a B-mode image signal of the image A for tissueimaging by processing the acoustic ray signal.

In step 107, transmission focusing is performed by tilting thetransmission beam to acquire each element reception signal, and theprocess proceeds to step 108. That is, according to the driving signalsupplied from the transmission unit 14, an ultrasound beam istransmitted from the probe 36. In this case, unlike in step 103, thetransmission beam is transmitted so as to be inclined. Then, theultrasound echo generated by interaction between the transmittedultrasound beam and the subject is received by the probe 36, the analogelement signal is amplified by the receiving unit 16, the amplifiedanalog element signal is converted into digital element data by the A/Dconversion unit 18, and the digital element data is stored in theelement data storage unit 20.

In step 108, the image B for needle imaging is generated by performingreception focusing in a direction, which is inclined by the angle θ withrespect to the transmission beam (inclined transmission beam), for thereception signal of each element, and the process proceeds to step 110.That is, the second reception focusing section 40B acquires each elementreception signal obtained by the inclined transmission beam from theelement data storage unit 20 and generates reception data (acoustic raysignal) by performing reception focusing in a direction that is furtherinclined by the angle θ with respect to the transmission beam, and thesecond detection processing section 40D generates a B-mode image signalof the image B for needle imaging by processing the acoustic ray signal.

In step 110, it is determined whether or not n=N. That is, it isdetermined whether or not the above processing has ended for all thescanning lines. When the determination is negative, the process proceedsto step 102 to repeat the above processing. When the determination ispositive, the process proceeds to step 112.

In step 112, the combination processing section 40E generates a displayimage of one frame by combining the image A and the image B, which havebeen generated as described above, by scan conversion, and the series ofprocesses are ended. A display image of the next frame is generated byperforming the process from the processing of step 100.

Thus, the ultrasound diagnostic device according to the third embodimentof the present disclosure requires two ultrasound transmissions unlikein each of the embodiments described above. Accordingly, it is possibleto reliably visualize a reflector, such as a needle at an angle thatcannot be visualized in each of the embodiments described above, otherthan the tissue. Therefore, since a reflector, such as a needle, can bereliably visualized, it is possible to compensate for the disadvantagesof the embodiments described above by performing mode switching or thelike when a reflector, such as a needle, other than the tissue cannot bedetected in the embodiments described above.

(Fourth Embodiment)

Subsequently, an ultrasound diagnostic device according to a fourthembodiment will be described.

In the fourth embodiment, reception focusing by the second receptionfocusing section 40B when using a convex type ultrasound probe in thethird embodiment will be described.

The reception focusing of the second reception focusing section 40B whentransmitting the transmission beam, which is inclined by the angle ϕ,using the convex type ultrasound probe will be described.

First, a case in which specular reflection is not assumed will bedescribed with reference to FIGS. 15A and 15B.

Assuming that the scanning line i is inclined by the angle ϕ,X-direction and Y-direction distances DX and DY of the reflection pointin a direction, which is further inclined by the angle θ, from thetransmission focus are given by the following equations (FIG. 15A).DX=(V×Tt−FD)×sin(ϕ+θ)DY=(V×Tt−FD)×cos(ϕ+θ)Tt=T0/2

Then, the X-direction and Y-direction distances of the reflection pointfrom the transmission focus of the scanning line (i +k) are calculated.

First, the X-direction and Y-direction distances of the transmissionfocus of the scanning line i with respect to the transmission focus ofthe scanning line (i+k) are calculated from FIG. 15B. The x and ycoordinates of the transmission focus of the scanning line i with theconvex center as the origin are as follows.x _(i) =FD×sin(ϕ)y _(i) =R+FD×cos(ϕ)

Here, R indicates the radius of the convex type ultrasound probe.

The scanning line (i+k) is inclined by the angle k×EP with respect tothe scanning line i. Accordingly, it can be seen from FIG. 15B that thescanning line i is inclined by the angle ϕ with respect to the ydirection while the scanning line (i+k) is inclined by ϕ+k×EP withrespect to the y direction (here, EP is an angle between the scanninglines, and k is a positive or negative value with the i-th scanning lineas 0). Therefore, the x and y coordinates of the transmission focus ofthe scanning line (i+k) are expressed as follows.x _(i+k) =R×sin(k×EP)+FD×sin(ϕ+k×EP)y _(i+k) =R×cos(k×EP)+FD×cos(ϕ+k×EP)

Based on the above equations, the X-direction and Y-direction distancesof the transmission focus of the scanning line i with respect to thetransmission focus of the scanning line (i+k) are calculated by thefollowing equations.x _(i) −x _(i) +k=FD×sin(ϕ)−R×sin(k×EP)−FD×sin(ϕ+k×EP)y _(i) −y _(i+k) =R+FD×cos(ϕ)−R×cos(k×EP)−FD×cos(ϕ+k×EP)

Therefore, the X-direction distance DX2 and Y-direction distance DY2 ofthe reflection point with respect to the transmission focus of thescanning line (i+k) are calculated by the following equations.DX2=DX+FD×sin(ϕ)−FD×sin(ϕ+k×EP)−R×sin(k×EP)DY2=DY+FD×cos(ϕ)−FD×cos(ϕ+k×EP)+R−R×cos(k×EP).

It can be seen that the time until the acoustic wave transmitted fromthe opening of the scanning line (i+k) reaches the reflection point isas follows.Tt2=(FD+sign(DY)×sqrt(DX2² +DY 2 ²))/V.

Here, when DY is negative, the acoustic wave reaches the reflectionpoint before forming the transmission focus. Accordingly, sign(DY) ismultiplied.

On the other hand, from FIG. 15B, it can be seen that the propagationtime of the acoustic wave, which returns from the reflection point tothe j-th element (has a positive or negative value with an elementcorresponding to the position of the scanning line (i+k) as 0) of theopening of the scanning line (i+k), is as follows.Tr=sqrt(X ² +Y ²)/V

Here, X=DX+FD×sin(ϕ)−R×sin((k+j)×EP), andY=DY+FD×cos(ϕ)+R−R×cos((k+j)×EP).

Here, EP is an angle between the scanning lines and is also an anglebetween elements.

Therefore, by adding up the signals of the respective elements of eachscanning line using the following equations, it is possible to extractthe reflected wave from the reflection point, that is, it is possible toperform reception focusing.RF(i, T0)=ΣΣELE(i+k, j, T)T=Tt2+Tr

Here, i+k indicates a scanning line, j indicates an element, one of twoΣ indicates integration on k, and the other Σ indicates integration onj.

That is, when transmitting the transmission beam that is inclined by theangle ϕ using the convex type ultrasound probe, reception focusing in adirection that is further inclined by the angle θ is performed so as tosatisfy the following equations.RF(i, T0)=ΣΣELE(i+k, j, T)T=Tt2+TrTr=sqrt(X ² +Y ²)/VX=DX+FD×sin(ϕ)−R×sin((k+j)×EP)Y=DY+FD×cos(ϕ)+R−R×cos((k+j)×EP)Tt2=(FD+sign(DY)×sqrt(DX2² +DY2²))/VDX2=DX+FD×sin(ϕ)−FD×sin(ϕ+k×EP)−R×sin(k×EP)DY2=DY+FD×cos(ϕ)−FD×cos(ϕ+k×EP)+R−R×cos(k×EP)DX=(V×Tt−FD)×sin(ϕ+θ)DY=(V×Tt−FD)×cos(ϕ+θ)Tt=T0/2

Next, a case in which reception focusing is performed in considerationof the fact that the reflected wave from the needle becomes an acousticwave equivalent to a case in which a sound source is present at thesymmetrical position with the needle as a specular reflection surfacewill be described with reference to FIGS. 16, 17A, and 17B.

Assuming that the scanning line i is inclined by the angle ϕ, distancesDX and DY of the reflection point in a direction, which is furtherinclined by the angle θ, from the transmission focus are given by thefollowing equations.DX=(V×Tt−FD)×sin(ϕ+θ)DY=(V×Tt−FD)×cos(ϕ+θ)Tt=T0/2

Then, a pseudo sound source is assumed at the symmetrical position ofthe transmission focus of the scanning line i+k with respect to theneedle, and distances DX3 and DY3 from the transmission focus of thescanning line i+k to the pseudo sound source are calculated.

For the above, first, DX2 and DY2 are calculated in FIG. 17A (or FIG.17B). Here, FIGS. 17A and 17B are diagrams for explaining the method ofcalculating DX2 and DY2, and FIG. 17B is an enlarged view of a portionsurrounded by the dotted line in FIG. 17A.

In order to calculate DX2 and DY2, first, the distance of the arrow A inFIG. 17B is calculated. For the above, first, the distance between thetransmission focus of the scanning line i+k and the transmission focusof the scanning line i and an angle β in FIG. 17B are calculated.

For the distance between the transmission focus of the scanning line i+kand the transmission focus of the scanning line i, referring to FIG.17A, it can be seen that the triangle formed by the convex center andthe transmission focuses is an isosceles triangle having the convexcenter as its apex. Assuming that the length of the side is Rb, it canbe seen that Rb is given by the following equation by the cosinetheorem.Rb=sqrt(R ² +FD ²+2×R×FD×cos(ϕ))

In addition, from the fact that the angle of the apex (convex center) ofthe isosceles triangle is k×EP, it can be seen that the distance betweenthe transmission focus of the scanning line i+k and the transmissionfocus of the scanning line i is given by the following equation.2×Rb×sin(k×EP/2)

Then, in order to calculate β in FIG. 17B, α1, α2, and α3 are calculatedfirst.

Since α1 is the base angle of the isosceles triangle described above, itcan be seen that α1 is 90°−(k×EP/2).

From FIG. 17B, it can easily be seen that α2 is 90°−ϕ−θ.

It can be seen that α3 is equal to α3 in FIG. 17A. In addition, it canbe seen that α3 in FIG. 17A is given by the following equation sinceRb/sin(180°−ϕ)=FD/sin(α3) is satisfied by the sine theorem.α3=arcsin(sin(ϕ)×FD/Rb)

From above, it can be seen that β is given by the following equation.

$\begin{matrix}{\beta = {{180{^\circ}} - {\alpha 1} - {\alpha 2} - {\alpha 3}}} \\{= {\left( {k \times {{EP}/2}} \right) + \phi + \theta - {\arcsin\left( {{\sin(\phi)} \times {{FD}/{Rb}}} \right)}}}\end{matrix}$

From above, it can be seen that the distance of the arrow A in FIG. 17Bis calculated by the following equation.2×Rb×sin(k×EP/2)×sin(β)

From above, DX2 and DY2 are given by the following equations.DX2=2×Rb×sin(k×EP/2)×sin(β)×sin(ϕ+θ)+DXDY2=2×Rb×sin(k×EP/2)×cos(β)×sin(ϕ+Θ)+DY

Here, β=(k×EP/2)+ϕ+θ−arcsin(sin(ϕ)×FD/Rb), andRb=sqrt(R²+FD²+2×R×FD×cos(ϕ)).

Since DX3 and DY3 are values obtained by doubling DX2 and DY2, DX3 andDY3 are expressed as follows.DX3=2×DX2DY3=2×DY2

The scanning line (i+k) is inclined by the angle k×EP with respect tothe scanning line i. Accordingly, it can be seen from FIG. 17A that thescanning line i is inclined by the angle ϕ with respect to the ydirection, while the scanning line (i+k) is inclined by ϕ+k×EP withrespect to the y direction (here, k is a positive or negative value withthe i-th scanning line as 0).

Therefore, the X-direction and Y-direction distances of the transmissionfocus to the origin of the scanning line (i+k) (center of the opening)are expressed as follows.FD×sin(ϕ+k×EP)FD×cos(ϕ+k×EP)

In addition, it can also be seen from FIG. 17A that the X-direction andY-direction distances of the origin of the scanning line (i+k) (centerof the opening) to the j-th element of the opening of the scanning line(i+k) are as follows.R×(sin(k×EP)−sin((k+j)×EP))R×(cos(k×EP)−cos((k+j)×EP))

From above, it can be seen that the propagation time of the acousticwave returning to the j-th element of the opening of the scanning line(i+k) from the sound source is as follows.Tr=sqrt(X ² +Y ²)/V

Here, X=DX3+FD×sin(ϕ+k×EP)+R×(sin(k×EP)−sin((k+j)×EP)), andY=DY3+FD×cos(ϕ+k×EP)+R×(cos(k×EP)−cos((k+j)×EP)).

Therefore, by adding up the signals of the respective elements of eachscanning line using the following equations, it is possible to extractthe reflected wave from the reflection point, that is, it is possible toperform reception focusing.RF(i, T0)=ΣΣELE(i+k, j, T)T=FD/V+Tr

Here, i+k indicates a scanning line, j indicates an element, one of twoΣ indicates integration on k, and the other Σ indicates integration onj.

That is, when performing reception focusing in consideration of the factthat the reflected wave from the needle becomes an acoustic waveequivalent to a case in which a sound source is present at thesymmetrical position with the needle as a specular reflection surface,the second reception focusing section 40B performs reception focusing soas to satisfy the following equations.RF(i, T0)=ΣΣELE(i+k, j, T)T=FD/V+TrTr=sqrt(X ² +Y ²)/VX=DX3+FD×sin(ϕ+k×EP)+R×(sin(k×EP)−sin((k+j)×EP))Y=DY3+FD×cos(ϕ+k×EP)+R×(cos(k×EP)−cos((k+j)×EP))DX3=2×DX2DY3=2×DY2DX2=2×Rb×sin(k×EP/2)×sin(β)×sin(ϕ+θ)+DXDY2=2×Rb×sin(k×EP/2)×cos(β)×sin(ϕ+θ)+DYDX=(V×Tt−FD)×sin(ϕ+θ)DY=(V×Tt−FD)×cos(ϕ+θ)

Here, β=(k×EP/2)+ϕ+θ−arcsin(sin(ϕ)×FD/Rb)

Rb =sqrt(R²+FD²+2×R×FD ×cos(ϕ))

In this case, as in the case of using the linear type ultrasound probe,it is possible to improve the needle visualization performance. However,the visualization performance of the needle tip is reduced.

In addition, since the flow of the process performed by the main part ofthe ultrasound diagnostic device according to the fourth embodimentbecomes the same process just by replacing the ultrasound probe in thethird embodiment with a convex type ultrasound probe, the detailedexplanation thereof will be omitted.

Setting ϕ=0 in the above equations when performing the receptionfocusing of the second reception focusing section 40B in the fourthembodiment corresponds to a case in which the transmission beam is notinclined. In addition, if integration on k is not performed, one ofelement reception signals that share the transmission focus is used.

In the case of the convex type ultrasound probe, the direction of thetransmission beam differs depending on each scanning line. That is, thedirections of the transmission beams spaced apart from each other by nelements are different by the angle n×EP. In consideration of thedifference between the transmission beam directions of the scanninglines, θ of each RF(i, T0) may be shifted so as to always performreception focusing in the same direction without depending on thescanning line in the above equations. That is, θ may be set as θ+n×EP, .. . , θ+EP, θ, θ−EP, . . . , θ−n×EP in reception focusing for generatingRF(i−n, T0), . . . , RF(i−1, T0), RF(i, T0), RF(i+1, T0), . . . ,RF(i+n, T0).

In each of the embodiments described above, the direction of thereception focus is set to θ. When sticking the needle in a state inwhich the needle is fixed to the needle guide or the like, θ determinedby the fixture may be set in advance through the operating unit 32 orthe like. When sticking the needle freehand, reception focusing may beperformed in plural directions to generate needle images, and an imagein which the needle is visualized best may be selected. As a method ofdetermining an image in which a needle is visualized best, an imageincluding the maximum brightness or an image having the maximum averagebrightness in the brightness distribution of a predetermined region inwhich it is assumed that a needle is included, an image that is linearlydetected by the Hough transform or the like and has the maximumbrightness in the straight line, or the like may be used.

In addition, an object to be visualized is not only the needle but alsoany reflector causing specular reflection. That is, in the reflectorcausing specular reflection, visualization may be reduced sincesufficient specular reflection does not return to the reception openingdepending on the transmission beam direction. However, as describedabove, using the fact that acoustic waves formed by transmissionfocusing propagate in various directions, it is possible to visualizethe reflector satisfactorily without extra transmission.

In addition, each of the embodiments described above is also effectivefor the visualization of a reflector that does not cause specularreflection. That is, conventionally, even when there is no reflectorbelow the probe and transmission steering (transmission with theinclined transmission beam) is required for visualization, visualizationcan be realized without performing extra transmission steering invarious directions using the fact that acoustic waves formed bytransmission focusing propagate not only to a region below the probe butalso to the reflector. In this case, since the acoustic wave thatspreads is used, the image quality is degraded compared with thetransmission steering. However, it is possible to improve the imagequality by using plural pieces of element data as in the secondembodiment.

Although the case of generating an image of the needle has beendescribed in each of the above embodiments, the present disclosure iseffective not only for the generation of an image of the needle but alsofor the detection of the direction of the needle. That is, it can bedetermined that, after generating needle images by performing receptionfocusing in plural directions, the needle is stuck in a directionperpendicular to a direction in which an image having a needlevisualized best is obtained. Alternatively, it is also possible toperform linear detection by the Hough transform or the like in an imagehaving a needle visualized satisfactorily and to determine the directionof the straight line to be the direction of the needle.

In each of the embodiments described above, the generation of a B-modeimage has been described. However, the present disclosure is effectivefor Doppler image generation as well as the B-mode image generation.

In addition, the processes performed by the respective units in each ofthe embodiments described above may be distributed as a program by beingstored in various storage media.

In addition, the configuration, operation, and the like of theultrasound diagnostic device described in each of the embodiments areexamples, and it is needless to say that these can be changed accordingto the circumstances within the scope not deviating from the spirit ofthe present disclosure.

All documents, patent applications, and technical standards described inthis specification are incorporated in this specification by referenceto the same extent as when the incorporation of individual documents,patent applications, and technical standards by reference is describedspecifically and individually.

What is claimed is:
 1. An ultrasound diagnostic device, comprising: aprobe including a plurality of elements that generate and transmitultrasound waves and receive ultrasound waves reflected from aninspection target; a transmission unit that transmits ultrasound wavesfrom the plurality of elements so as to form a plurality of ultrasoundbeams that converge at a single transmission focus and diverge from thesingle transmission focus, wherein the single transmission focus isassociated with a predetermined direction; a memory; and a processorcoupled with the memory, wherein the processor is configured to performfirst reception focusing for each reception signal received by eachelement of the probe according to reflection in a reception focusingdirection that is different from the predetermined direction, thereception focusing direction being a direction that passes through thetransmission focus and is inclined by an angle with respect to thepredetermined direction, and to determine a direction of a needle basedon a result of the first reception focusing.
 2. The ultrasounddiagnostic device according to claim 1, wherein the processor is furtherconfigured to: perform second reception focusing according to reflectionin the predetermined direction.
 3. The ultrasound diagnostic deviceaccording to claim 2, wherein the processor is further configured to:combine results of the first reception focusing and the second receptionfocusing.
 4. The ultrasound diagnostic device according to claim 1,wherein the processor is further configured to perform the firstreception focusing based on a delay time set.
 5. The ultrasounddiagnostic device according to claim 1, wherein the processor is furtherconfigured to perform the first reception focusing based on anassumption that there is specular reflection at each point in thereception focusing direction, and based on an assumption that there is asound source at a second point that is different from each point in thereception focusing direction, and perform reception focusing for eachpoint in the reception focusing direction based on a delay time for theassumed sound source.
 6. The ultrasound diagnostic device according toclaim 1, further comprising: an operating unit that is configured toreceive a user designation of the reception focusing direction.
 7. Theultrasound diagnostic device according to claim 6, wherein the operatingunit is configured to receive the user designation of the receptionfocusing direction based on information related to a fixed direction ofthe needle.
 8. The ultrasound diagnostic device according to claim 6,wherein the operating unit receives the user designation of thereception focusing direction based on a result of last first receptionfocusing performed by the processor.
 9. An ultrasound diagnostic method,comprising: transmitting ultrasound waves from a plurality of elementsof a probe so as to form a plurality of ultrasound beams that convergeat a single transmission focus and diverge from the single transmissionfocus, the probe including the plurality of elements that generate andtransmit ultrasound waves and receive ultrasound waves reflected from aninspection target; and wherein the single transmission focus isassociated with a predetermined direction; performing first receptionfocusing for each reception signal received by each element of the probeaccording to reflection in a reception focusing direction that isdifferent from the predetermined direction, the reception focusingdirection being a direction that passes through the transmission focusand is inclined by an angle with respect to the predetermined direction,and determining a direction of a needle based on a result of the firstreception focusing.
 10. The ultrasound diagnostic method according toclaim 9, further comprising: performing second reception focusingaccording to reflection in the predetermined direction.
 11. Theultrasound diagnostic method according to claim 10, further comprising:combining results of the reception focusing of the first receptionfocusing and the second reception focusing.
 12. The ultrasounddiagnostic method according to claim 9, wherein the performing of thefirst reception focusing further includes performing reception focusingbased on a delay time set.
 13. The ultrasound diagnostic methodaccording to claim 9, wherein the performing of the first receptionfocusing further includes performing the first reception focusing basedon an assumption that there is specular reflection at each point in thereception focusing direction, and based on an assumption that there is asound source at a second point that is different from each point in thereception focusing direction, and performing reception focusing for eachpoint in the reception focusing direction based on a delay time for theassumed sound source.
 14. The ultrasound diagnostic method according toclaim 9, further comprising: designating the reception focusingdirection.
 15. The ultrasound diagnostic method according to claim 14,wherein the designating of the other direction further includesdesignating the reception focusing direction based on informationrelated to a fixed direction of the needle.
 16. The ultrasounddiagnostic method according to claim 14, wherein the designating of thereception focusing direction further includes designating the receptionfocusing direction based on a result of the first second receptionfocusing that has been performed last time.
 17. A non-transitory storagemedium storing an ultrasound diagnostic program that causes a computerto execute processing comprising: controlling transmission of ultrasoundwaves from a plurality of elements of a probe so as to form a pluralityof ultrasound beams that converge at a single transmission focus anddiverge from the single transmission focus, the probe including theplurality of elements that generate and transmit ultrasound waves andreceive ultrasound waves reflected from an inspection target; andwherein the single transmission focus is associated with a predetermineddirection; performing first reception focusing for each reception signalreceived by each element of the probe according to reflection in areception focusing direction that is different from the predetermineddirection, the reception focusing direction being a direction thatpasses through the transmission focus and is inclined by an angle withrespect to the predetermined direction, and determining a direction of aneedle based on a result of the first reception focusing.
 18. Thestorage medium according to claim 17, wherein the processing furtherincludes performing second reception focusing according to reflection inthe predetermined direction.
 19. The storage medium according to claim18, wherein the processing further includes combining results of thereception focusing of the first reception focusing and the secondreception focusing.
 20. The storage medium according to claim 17,wherein the performing of the first reception focusing further includesperforming reception focusing based on a delay time set.
 21. Theultrasound diagnostic program according to claim 17, wherein theperforming of the first reception focusing further includes performingthe first reception focusing based on an assumption that there isassuming specular reflection at each point in the reception focusingdirection, and based on an assumption that there is assuming a soundsource at a different second point that is different from each point inthe reception focusing direction, and performing reception focusing foreach point in the reception focusing direction based on a delay time forthe assumed sound source.
 22. The ultrasound diagnostic programaccording to claim 17, wherein the processing further includesdesignating the reception focusing direction.
 23. The ultrasounddiagnostic program according to claim 22, wherein the designating of theother direction further includes designating the reception focusingdirection based on information related to a fixed direction of theneedle.
 24. The ultrasound diagnostic program according to claim 22,wherein the designating of the reception focusing direction furtherincludes designating the reception focusing direction based on a resultof the first second reception focusing that has been performed lasttime.